Well you are better than 1/2 way there , don't stop now
The repair manual is here under Tecumseh
K & C parts
Find an IPL and check that all of the case bolts are out
After that it is just a matter of prying on the pry places ( in manual ) till it splits .
Replace the lubricant and the seal if there is one .
The cases are genrerally held together with silicon .
Dumping the whole thing in petrol for a day or two will soften the silicon a bit.
Same story for cleaning the surface
A scoth brite pad dipped in petrol will generally shift the goo
And yes I LOATHE SILICON to .